1. Field of the Invention
The invention relates to a method for the production marking of liquid crystal displays (LCD) whereby the closure bar of the liquid crystal cell is produced by the screen printing process.
2. Description of the Prior Art
Liquid crystal displays have typically been formed by sandwiching a liquid crystal material between transparent plates. A closure bar, formed by screen printing, has typically been used to seal the peripheral edges of the sandwich. Such a liquid crystal display is illustrated in U.S. Pat. No. 3,995,941 in which the closure bar is a low melting point glass, the disclosure of which is hereby incorporated by reference.
Liquid crystal displays have hitherto generally been marked by means of a lettering machine so that the week number and year of manufacture were printed on them. This lettering is necessary in order to ensure watch identification for customer warranty purposes. With a fairly large production volume, a plurality of lettering machines with a plurality of operators must be employed, otherwise a production bottleneck can result.
Recently it has been proposed to superimpose a production code in the photoresist process for the segmentation of the electrode layer. But this involves two difficulties:
(a) The exposure occurs by multiple process, so that a corresponding multiple pattern must be typed and produced once per week; PA1 (b) Several weeks may elapse between electrode segmentation and further processing.